/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.discovery.resource.names;

import java.util.HashMap;

import org.apache.commons.discovery.ResourceNameDiscover;
import org.apache.commons.discovery.ResourceNameIterator;
import org.apache.commons.discovery.log.DiscoveryLogFactory;
import org.apache.commons.discovery.tools.ManagedProperties;
import org.apache.commons.logging.Log;


/**
 * Recover resource name from Managed Properties,
 * using OLD property names.
 * 
 * This class maintains a mapping between old names and
 * (new) the class names they represent.  The discovery
 * mechanism uses the class names as property names.
 * 
 * @see org.apache.commons.discovery.tools.ManagedProperties
 * 
 * @author Richard A. Sitze
 */
public class DiscoverNamesInAlternateManagedProperties
    extends ResourceNameDiscoverImpl
    implements ResourceNameDiscover
{
    private static Log log = DiscoveryLogFactory.newLog(DiscoverNamesInAlternateManagedProperties.class);
    public static void setLog(Log _log) {
        log = _log;
    }

    HashMap<String, String> mapping = new HashMap<String, String>();
    
    /** Construct a new resource discoverer
     */
    public DiscoverNamesInAlternateManagedProperties() {
    }
    
    /**
     */
    public void addClassToPropertyNameMapping(String className, String propertyName) {
        mapping.put(className, propertyName);
    }

    /**
     * @return Enumeration of ResourceInfo
     */
    public ResourceNameIterator findResourceNames(final String resourceName) {
        final String mappedName = mapping.get(resourceName);

        if (log.isDebugEnabled()) {
            if (mappedName == null) {
                log.debug("find: resourceName='" + resourceName + "', no mapping");
            } else {
                log.debug("find: resourceName='" + resourceName + "', lookup property '" + mappedName + "'");
            }
        }

        return new ResourceNameIterator() {
            private String resource =
                (mappedName == null) ? null : ManagedProperties.getProperty(mappedName);
            
            public boolean hasNext() {
                return resource != null;
            }
            
            public String nextResourceName() {
                String element = resource;
                resource = null;
                return element;
            }
        };
    }
}
